Surfaces with antimicrobial properties are of interest for medical facilities, medical devices, and even homes and household items to reduce the transmission of diseases and other malaise from one organism to another organism through common contact with the surface. Microbes generally have a limited lifetime on a surface; however that lifetime is generally for at least a few hours and is often in the order of days. Even when the microbes survive for hours significant contact can occur over that period. The most prevalent technologies used for antimicrobial surfaces include: silver ion technology; organic biocides in coatings or incorporated into objects; and cationic biocides covalently bonded to a reactive silicone compounds.
Silver ion technology in its simplest form is a coating system formed by binding silver ions to a fine ceramic powder, dispersed in a carrier. The silver ions, which can interrupt critical functions of microorganisms, are then exchanged with other ions when the surface comes into contact with aqueous fluids. This technology has been used to treat steel ducting and components in HVAC systems, building materials, laminates, floors, walls, paints, carpets, cubicle curtains, lockers, safety cabinets, bedpans, sack holders, soap dispensers, keypads, medical devices, wound dressings and implants.
Organic biocides have been incorporated into plastic and fabrics during manufacture. The concentration of biocide is optimized to provide adequate protection. Many different organic biocides are now in use, some specially selected for specific applications. Some of the earliest applications involved combating the growth of odor causing bacteria on medical devices. Applications for the building industry include wall laminates, for hospital environments include bedding, bed frames, carts for transport of medication, linens, hand rails, pulls, trims, door handles, slings, hoists, window blinds, dental trays, incise drapes, wound dressings, keyboards and other equipment.
Biocides covalently bonded to a reactive silicone compound are fixed onto a surface as an extremely thin film with little effect to the physical properties of the surface. Fixation of the biocide is important where toxicity, taint and other organoleptic aspects are of concern. This method is a bacteriostatic surface treatment that allows and requires normal cleaning procedures to maintain the biocidal activity of the surface. The technology has been used for treatment of bedsheets, hospital garments, curtains, floor and wall materials, air filtration systems, medical devices, bandages, surgical instruments and implants. The technique has been used to prevent biofilm growth on catheters, stents, contact lenses and endotracheal tubes.
These technologies can suffer from toxicity to organisms other than the microbes or promote formation of resistant strains of the microbes. Recently, light activated antimicrobial agents such as the dye indocyanine green have been found to be highly potent only when light activated, harmless to the organism and not believed to promote resistance due to the light only toxicity to the microbes. Polymeric materials generally display low toxicity to organisms and can be readily fixed to surfaces. Light activated antimicrobial polymeric materials have been reported, generally consisting of small molecule antimicrobials included in a polymeric carrier, but are not covalently bonded to the polymer. Antimicrobial polymers have the potential to exist in many different structural forms where enhancements, such as the surface area to volume, can significantly increase their activity toward microbes relative to surface fixed antimicrobial agent. Hence, a polymer that is a high molecular weight light activated antimicrobial agent is an attractive solution to many limitations of present antimicrobial system.